Raynaud's phenomenon patients experience episodic attacks that cause the blood vessels in the fingers and toes to constrict, limiting blood flow to the extremities, and potentially leading to permanent loss of function. During attacks, which are triggered in response to exposure to a cold environment, insufficient digital surface tissue blood flow may cause patients to experience skin color changes, numbness, and cold fingers and toes. Treatments are intended to reduce the number and severity of episodic attacks, and to prevent permanent damage. Raynaud's phenomenon attacks affect approximately five to ten percent of the population in the United States.
Traditionally, treatments are subjectively evaluated by asking patients to estimate the frequency and severity of Raynaud's attacks. Since each patient's subjective interpretation of an attack can vary widely, determining the efficacy of a particular treatment is problematic.
What is needed is a method for measuring surface skin temperature, as an indication of digital blood flow, in an ambulatory setting that will provide an objective indication of treatment efficacy during clinical trials, and provide valuable information during a drug approval process, for instance.